%Oppgave 7a)

fun {Length Ls}
   case Ls
   of nil then 0
   [] _|Lr then 1 + {Length Lr}
   end
end

%Oppgave 7b)

fun {Take Xs N}
   if N==0 then
      nil
   else
      case Xs
      of nil then nil
      [] Ls|Xr then Ls|{Take Xr N-1}
      end
   end
end

%Oppgave 7c)

fun {Drop Xs N}
   if N==0 then
      Xs
   else
      case Xs
      of nil then nil
      [] _|Xr then {Drop Xr N-1}
      end
   end
end

%Oppgave 7d)

fun {Append Xs Ys}
   case Xs
   of nil then Ys
   [] Ls|Xr then Ls|{Append Xr Ys}
   end
end

%Oppgave 7e)

fun {Member Xs Y}
   if Xs == nil then
      false
   elseif Xs.1 == Y then
      true
   else
      {Member Xs.2 Y}
   end
end

%Oppgave 7f)

fun {Position Xs Y}
   if Xs.1 == Y then 1
   else 1 + {Position Xs.2 Y}
   end
end

%Oppgave 8

fun {Tokenize L}
   if L == nil then nil
   elseif {Member ["local" "then" "in" "if" "end" "else" "elseif" "skip"] L.1} then "key("#L.1#")"|{Tokenize L.2}
   elseif {Member ["+" "-" "/" "*"] L.1} then  "op("#L.1#")"|{Tokenize L.2}
   elseif L.1 == "=" then "un("#L.1#")"|{Tokenize L.2}
   elseif L.1 == "==" then "sammenligning(==)"|{Tokenize L.2}
   elseif L.1.1 >= &A andthen L.1.1 =< &Z then "id("#L.1#")"|{Tokenize L.2}
   elseif L.1.1 >= &a andthen L.1.1 =< &z orelse L.1.1 == "'" then "atom("#L.1#")"|{Tokenize L.2} %L.1.1 - Første bosktav i første ord
   else 'Error, error! System will self destruct in 5 seconds'
   end
end